With the popularization of the Internet, network connection becomes an important part of daily life. Wireless network connection that is not subjected to any physical and location constraint is getting prevailing. Further, various portable electronic devices, such as personal digital assistant (PDA), mobile phone, and notebook computer, are made compact and light-weighted generation by generation, providing enhanced portability and as a consequence, wireless techniques are now expanded to wide applications.
Nowadays, various communication protocols set in accordance with the specifications and standards of various wireless digital transmission techniques, such as WLAN (Wireless Local Area Network), Bluetooth, HyperLAN, and IEEE (Institute of Electrical and Electronics Engineers), are employed in wireless communication. And, to provide satisfactory wireless communication on the basis of these protocols, various designs of antenna are available.
The currently available antenna can be classified as dipole antenna, monopole antenna, planar antenna, loop antenna, and disk antenna. Various techniques have been developed for all these kinds of antenna. For patent documents that are currently known, Taiwan Patent Publication No. M241815 discloses a dual-band monopole antenna, wherein the dual-band monopole antenna comprises a substrate, a dual frequency resonance antenna unit, a metal line, and a grounding metal line. The substrate defines a vertical direction and a horizontal direction. The dual frequency resonance antenna unit is comprised of a low-frequency radiation element and a high-frequency radiation element.
The two radiation elements of the dual frequency resonance antenna unit are made up of lines of different lengths and are formed on the substrate in a direction substantially parallel to the vertical direction of the substrate. The dual frequency resonance antenna unit receives vertical polarization components of the high-frequency and low-frequency signals respectively. The line length of the low-frequency radiation element is greater than that of the high-frequency radiation element. Both the low-frequency and the high-frequency radiation elements can be formed as repeatedly curved/bent metal traces.
The metal line is of an L-shape and is formed on the substrate. A long branch of the metal line is substantially parallel to the substrate horizontal direction and connected to terminals of the two radiation elements of the dual frequency resonance antenna unit for connection with a signal feeding line of a coaxial cable. A short branch of the metal line is arranged in a direction parallel to the substrate vertical direction.
The grounding metal line is formed on the substrate and is substantially parallel to the substrate horizontal direction and is connected to the short branch of the metal line for connection with a shielding metal layer of the coaxial cable.
The metal line and the grounding metal line are arranged at unsymmetrical locations to connect to the signal feeding line and the shielding metal layer of the coaxial cable so that the horizontal polarization components do not compensate each other.